Dataset Information

IgG4 drives M2a macrophages to a regulatory M2b-like phenotype: potential implication in immune tolerance.

ABSTRACT:

Background

Macrophages can be converted in vitro into immunoregulatory M2b macrophages in the presence of immune complexes (ICs), but the role of the specific subclasses IgG1 or IgG4 in this phenotypic and functional change is not known.

Objective

We aimed to refine the original method by applying precisely defined ICs of the subclasses IgG4 or IgG1 constructed by two independent methods.

Methods

Monocyte-derived macrophages (MDMs) were treated with M-CSF, followed by IL-4/IL-13 to induce the M2a allergic phenotype. To mimic unspecific or allergen-specific ICs, plates were coated with myeloma IgG1 or IgG4, or with grass pollen allergen Phl p 5 followed by recombinant human Phl p 5-specific IgG1 or IgG4. M2a polarized macrophages were then added, cultured, and examined for cellular markers and cytokines by flow cytometry, ELISA, and rtPCR. Alternatively, immune complexes with IgG1 or IgG4 were formed using protein L.

Results

IgG4 ICs down regulated CD163 and CD206 on M2a cells, and significantly increased IL-10, IL-6, TNF?, and CCL1 secretion, indicating a shift to an M2b-like phenotype. Treatment with IgG4 ICs resulted in expression of Fc?RII and down modulation of Fc?RII compared with IgG1 treated cells (P = 0.0335) or untreated cells (P < 0.00001).

Conclusion

Immune complexes with subclasses IgG1 and IgG4 can in vitro be generated by plate absorption, and in fluid form by protein L. Cross-linking of Fc?RIIb by the IgG4 subclass redirects pro-allergic M2a macrophages to an M2b-like immunosuppressive phenotype. This suggests an interplay of macrophages with IgG4 in immune tolerance, likely relevant in allergen immunotherapy.

SUBMITTER: Bianchini R

PROVIDER: S-EPMC6492166 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

IgG4 drives M2a macrophages to a regulatory M2b-like phenotype: potential implication in immune tolerance.

Bianchini Rodolfo R Roth-Walter Franziska F Ohradanova-Repic Anna A Flicker Sabine S Hufnagl Karin K Fischer Michael Bernhard MB Stockinger Hannes H Jensen-Jarolim Erika E

Allergy 20181128 3

<h4>Background</h4>Macrophages can be converted in vitro into immunoregulatory M2b macrophages in the presence of immune complexes (ICs), but the role of the specific subclasses IgG1 or IgG4 in this phenotypic and functional change is not known.<h4>Objective</h4>We aimed to refine the original method by applying precisely defined ICs of the subclasses IgG4 or IgG1 constructed by two independent methods.<h4>Methods</h4>Monocyte-derived macrophages (MDMs) were treated with M-CSF, followed by IL-4/ ...[more]

PMID: 30338531

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Project description:BackgroundWe recently reported a novel IgG4-centered immune evasion mechanism in cancer, and this was achieved mostly through the Fc-Fc reaction of increased IgG4 to cancer-bound IgG in cancer microenvironment. The mechanism was suggested to be related to cancer hyperprogressive disease (HPD) which is a side-effect often associated to IgG4 subtype PD-1 antibody immunotherapy. HPD was reported to occur in cancers with certain mutated genes including KRAS and such mutations are often associated to glutathione (GSH) synthesis. Therefore, we hypothesize that IgG4 and GSH may play a synergistic role in local immunosuppression of cancer.MethodsQuantitatively analyzed the distribution and abundance of GSH and IgG4 in human cancer samples with ELISA and immunohistochemistry. The interactions between GSH and IgG4 were examined with Electrophoresis and Western Blot. The synergistic effects of the two on classic immune responses were investigated in vitro. The combined effects were also tested in a lung cancer model and a skin graft model in mice.ResultsWe detected significant increases of both GSH and IgG4 in the microenvironment of lung cancer, esophageal cancer, and colon cancer tissues. GSH disrupted the disulfide bond of IgG4 heavy chain and enhanced IgG4's ability of Fc-Fc reaction to immobilized IgG subtypes. Combined administration of IgG4 and GSH augmented the inhibitory effect of IgG4 on the classic ADCC, ADCP, and CDC reactions. Local administration of IgG4/GSH achieved the most obvious effect of accelerating cancer growth in the mouse lung cancer model. The same combination prolonged the survival of skin grafts between two different strains of mouse. In both models, immune cells and several cytokines were found to shift to the state of immune tolerance.ConclusionCombined application of GSH and IgG4 can promote tumor growth and protect skin graft. The mechanism may be achieved through the effect of the Fc-Fc reaction between IgG4 and other tissue-bound IgG subtypes resulting in local immunosuppression. This reaction was facilitated by increased GSH to dissociate the two heavy chains of IgG4 Fc fragment at its disulfide bonds. Our findings unveiled the interaction between the redox system and the immune systems in cancer microenvironment. It offers a sensible explanation for HPD and provides new possibilities for manipulating this mechanism for cancer immunotherapy.

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Dataset Information

IgG4 drives M2a macrophages to a regulatory M2b-like phenotype: potential implication in immune tolerance.

Background

Objective

Methods

Results

Conclusion

Publications

IgG4 drives M2a macrophages to a regulatory M2b-like phenotype: potential implication in immune tolerance.

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